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Mozilla Firefox CVE-2026-12296

| EUVDEUVD-2026-37087 CRITICAL
Protection Mechanism Failure (CWE-693)
2026-06-16 mozilla GHSA-2xx6-2jh9-8wmx
Information Disclosure Mozilla
9.6
CVSS 3.1 · Vendor: mozilla
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Severity by source

Vendor (mozilla) PRIMARY
9.6 CRITICAL
AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
vuln.today AI
8.3 HIGH

Network-reachable via malicious content with required user interaction, but AC:H because a prior content-process compromise is needed to weaponize the sandbox escape; scope changes and impact is total.

3.1 AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
SUSE
8.8 CRITICAL
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
Analysis Generated
Jul 23, 2026 - 16:46 vuln.today
CVE Published
Jun 16, 2026 - 11:52 cve.org
CRITICAL 9.6
CVE Published
Jun 16, 2026 - 11:52 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152 and Firefox ESR 140.12.

AnalysisAI

Sandbox escape in Mozilla Firefox's Process Sandboxing security component allows a remote attacker to break out of the content process isolation boundary, escalating from a compromised renderer to broader system access after a user visits a malicious page. Affects Firefox before version 152 and Firefox ESR before 140.12; the CVSS 3.1 base score is 9.6 (scope-changed, high impact across confidentiality, integrity, and availability). There is no public exploit identified at time of analysis and EPSS exploitation probability is low (0.15%, 5th percentile), consistent with CISA SSVC scoring exploitation as 'none.'

Technical ContextAI

The affected component is Firefox's Security: Process Sandboxing subsystem, which enforces privilege separation between low-privilege content/renderer processes and the higher-privilege parent process. The CWE-693 classification (Protection Mechanism Failure) indicates the root cause is a failure of that security control itself rather than a memory-corruption primitive per se - the sandbox boundary can be bypassed, letting code that should be confined to a content process reach resources or the parent process it should not. The CPE cpe:2.3:a:mozilla:firefox identifies all Firefox builds prior to the fixed releases as affected; because ESR (Extended Support Release) shares the underlying platform, ESR 140.x is separately affected and patched. Sandbox escapes are typically chained: an attacker first needs code execution or a strong primitive inside the sandboxed content process, then uses this flaw to cross the isolation boundary - reflected by the CVSS Scope:Changed metric.

RemediationAI

Apply the vendor patch: upgrade to Firefox 152 or Firefox ESR 140.12 or later, which Mozilla identifies as the fixed releases. On enterprise Linux, install the corresponding distribution updates - Red Hat via RHSA-2026:27733/27717/27734/29940/30846 (https://access.redhat.com/security/cve/CVE-2026-12296) and SUSE via SUSE-SU-2026:2582/2583 (https://www.suse.com/support/update/SUSE-SU-2026:2582/). Consult Mozilla advisory MFSA 2026-57 (https://www.mozilla.org/security/advisories/mfsa2026-57/) for release details. Because exploitation requires the user to visit malicious content, effective interim compensating controls until patching completes include enforcing strict content controls - deploy or keep Firefox's site isolation and default sandbox settings enabled (do not weaken process count or sandbox level via policy), and use enterprise policy or a web proxy to block untrusted/unknown sites and script from unvetted origins; the trade-off is reduced browsing flexibility for users. Disabling JavaScript on untrusted sites via NoScript-style controls further reduces the likelihood of the prerequisite content-process compromise, at the cost of site functionality. These are stopgaps only - the reliable fix is the version upgrade.

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Same weakness CWE-693 – Protection Mechanism Failure

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Same technique Information Disclosure

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Liberty Linux 8 Fixed
SUSE Liberty Linux 9 Fixed
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Desktop Applications 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed

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CVE-2026-12296 vulnerability details – vuln.today
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